Gauss–Seidel limb scattering (GSLS) radiative transfer model development in support of the Ozone Mapping and Profiler Suite (OMPS) limb profiler mission

摘要

The Gauss–Seidel limb scattering (GSLS) radiative transfer (RT) modelsimulates the transfer of solar radiation through the atmosphere and isimbedded in the retrieval algorithm used to process data from the OzoneMapping and Profiler Suite (OMPS) limb profiler (LP), which was launched onthe Suomi NPP satellite in October 2011. A previous version of this model hasbeen compared with several other limb scattering RT models in previousstudies, including Siro, MCC++, CDIPI, LIMBTRAN, SASKTRAN, VECTOR, andMcSCIA. To address deficiencies in the GSLS radiance calculations revealed inearlier comparisons, several recent changes have been added that improve theaccuracy and flexibility of the GSLS model, including1. improved treatment of the variation of the extinction coefficient withaltitude, both within atmospheric layers and above the nominal top of theatmosphere;2. addition of multiple-scattering source function calculations at multiplesolar zenith angles along the line of sight (LOS);3. introduction of variable surface properties along the limb LOS, withminimal effort required to add variable atmospheric properties along the LOSas well;4. addition of the ability to model multiple aerosol types within the model atmosphere.The model improvements 1 and 2 are verified by comparison topreviously published results (using standard radiance tables wheneverpossible), demonstrating significant improvement in cases for which previousversions of the GSLS model performed poorly. The single-scattered radianceerrors that were as high as 4% in earlier studies are now generallyreduced to 0.3%, while total radiance errors generally decline from10% to 1–3%. In all cases, the tangent height dependence of theGSLS radiance error is greatly reduced.